A viewing angle range (hereinafter referred to as viewing angle) is an important performance index of a liquid crystal display panel. In the liquid crystal display panel, a polarization state of light can be changed through regulating an alignment of liquid crystal molecules. In this manner, a flux between an upper polarizer layer and a lower polarizer layer can be controlled, and the display function can be realized. Due to the influence of optical anisotropy of the liquid crystal molecules, the viewing angle of the liquid crystal display device is smaller than that of a cathode-ray tube display device. With the development of technology, in order to enlarge the viewing angle of the liquid crystal display device, multi-domain vertical alignment (MVA) mode, in-plane switching (IPS) mode, and fringe field switching (FFS) mode have been brought about successively, and wide viewing angle display of the liquid crystal display device has been realized.
Although wide viewing angle has become the trend for the development of liquid crystal display device, under certain circumstances, it is required that the liquid crystal display device has the function of switching between wide viewing angle and narrow viewing angle. As to portable electronic devices using liquid crystal display, such as cell phones, palmtops, and laptops, such requirement is especially urgent. For example, there are times when the user needs to share images on the portable electronic device with others and there are other times when he/she does not want others to see the images on the portable electronic device for the privacy sake. Therefore, it is necessary to provide a liquid crystal display panel with adjustable viewing angle.
In the prior art, in order to realize switching between wide viewing angle and narrow viewing angle, the following solutions are proposed.
1. Using shutter barrier film. When it is hoped that the liquid crystal panel displays images under narrow viewing angle, the user places the shutter barrier film on the screen of the liquid crystal display panel. Such approach requires the user to carry the shutter barrier film along, and thus is very inconvenient to operate.
2. Using double backlight system. In a double backlight system, a common backlight system is used to realize a wide angle display and another alignment backlight system is used to realize narrow angle display. However, in such method, the production cost, thickness and the energy consumption of the liquid crystal display panel will be increased undoubtedly.
3. Using asymmetrical electrodes, i.e., combining asymmetrical electrodes with corresponding driving methods. In such method, multiple electrode drivers are generally needed, which are complicated to be realized.
The abovementioned liquid crystal display panel cannot satisfy requirements for portable electronic devices in both aspects of size and power consumption. In the prior art, there are liquid crystal display panels that adopt two-phase pixel technology, which enables liquid crystal molecules to deflect to a certain angle by controlling the voltage of the electrode on the lower substrate, so as to realize switching between the wide viewing angle mode and the narrow viewing angle mode. FIG. 1 schematically shows a deflection of liquid crystal molecules under an action of an electric field in the liquid crystal display panel. A liquid crystal layer is arranged between an upper substrate 10 and a lower substrate 20, and pixel units are divided into a main pixel area 100 and a sub pixel area 200. A planar common electrode 110 and a bar-shaped pixel electrode 120 are arranged on the lower substrate corresponding to the two pixel areas, and an insulation layer 112 is arranged between the common electrode 110 and the pixel electrode 120 as a barrier. Electric field generated from different voltages on the common electrode 110 and the pixel electrode 120 will act on the liquid crystal molecules. However, the electric field generated as such is rather weak, and thus a viewing angle control effect obtained therein is poor.
The present disclosure proposes a new liquid crystal display panel with an adjustable viewing angle and a method for controlling the viewing angle so as to satisfy the demand of portable electronic device for circuit stability, weight and power consumption thereof.